Jumping sodium

Sodium reacting with water in octane

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Key concepts

A chemical reaction

The reaction of an alkali metal (Group 1) with water

Advanced: An example of a redox reaction



Sodium metal. Store in paraffin oil. Cut with a dry surface and knife.

Phenolphthalein indicator


An alkane such as octane which is less dense than water. Handle with care: Highly flammable


Chemical equation

Simple: Word equation and balanced equation

Sodium metal and water → Hydrogen and sodium hydroxide

2Na(s) + 2H2O(l) → H2(g) + 2NaOH(aq)

Advanced: This is an example of a redox reaction

Oxidationa and reduction half equations. 

Sodium is oxidized. 2Na(s) → 2e-

Water is reduced:  2e-+ 2H2O(l) → H2(g) + 2OH-(aq)



Sodium does not react with alkanes such as octane. The sodium passes through the liquid octane until it comes in contact with the water. Sodium reacts with the water producing hydrogen gas and sodium hydroxide. See the above equation. Sodium hydroxide is an alkali and changes the phenolphthalein indicator to pink. The hydrogen bubbles attach themselves to the sodium metal causing the piece of sodium to rise through the octane. When the sodium nears the surface of the octane the hydrogen gas is lost and the cycle repeats again.


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